The use of wax coatings enriched with antifungals has significantly contributed to quality maintaining of harvested citrus fruit. On the other hand, interest in essential oils (EOs) as an alternative to ... [more ▼]

The use of wax coatings enriched with antifungals has significantly contributed to quality maintaining of harvested citrus fruit. On the other hand, interest in essential oils (EOs) as an alternative to synthetic fungicides has recently gained momentum. In this study, Cinnamomum zeylanicum EO was incorporated into a variety of commercial citrus waxes (shellac, carnauba, paraffin and polyethylene). The biological activity of these formulations against green and blue rots as well as their viscosity and adherence to the orange fruit surface were evaluated. Excellent disease control was achieved with C. zeylanicum EO incorporated in shellac and/or carnauba wax compared to other EO–wax formulations. Disease control by EO–waxes seems to depend not only on the volume that remains on the fruit skin, but also, probably on the retention of EO components on the fruit. Other factors such as formulation solubility, permeability to gases, and compatibility between EO compounds and those of waxes may also be involved in the improvement of EO efficacy. The present study may therefore allow a careful selection of ppropriate waxes for the elaboration of effective EO–wax formulations. [less ▲]

Essential yield components of potato crops are influenced by the physiological age of the tubers at planting. Previous studies have attempted to develop biophysical, physiological or biochemical markers ... [more ▼]

Essential yield components of potato crops are influenced by the physiological age of the tubers at planting. Previous studies have attempted to develop biophysical, physiological or biochemical markers of potato tuber ageing. This research note focuses on characterising a physiological age index (PAI) based on sprouting parameters and originally developed by Caldiz et al. [Caldiz, D.O., Fernandez, L.V., Struik, P.C., 2001. Physiological age index: a new, simple and reliable index to assess the physiological age of seed potato tubers based on the haulm killing date and length of the incubation period. Field Crop. Res. 69, 69–79]. The PAI progression of two cultivars (‘Bintje’ and ‘Désirée’) was measured and modelled over 2 harvest years. The preliminary results were consistent with other ageing markers such as the incubation period (IP) and desprouting sensitivity. Under our experimental conditions, the PAI allowed us to describe cultivar-specific and harvest year-specific age variations measured from the time the haulm (foliage) was killed and the mother plant's influence on the tubers was no longer present. By contrast, the IP data displayed a higher inherent variability that impaired their discrimination ability. Critical PAI values corresponding to the main postharvest developmental steps (e.g., dormancy, apical dominance, multiple sprouting) were then identified on the basis of emergence pattern data, allowing us to propose this index as a useful reference frame for future ageing studies. [less ▲]

This paper presents a method based on quadratic discriminant analysis to select the best filters for detecting a wide range of defects in 'Jonagold' apple fruit using a multi-spectral vision system ... [more ▼]

This paper presents a method based on quadratic discriminant analysis to select the best filters for detecting a wide range of defects in 'Jonagold' apple fruit using a multi-spectral vision system. Reflectance spectra of damaged and sound tissue were recorded using a visible/NIR spectrometer. Analysed defects consisted of scald, hail damage (with and without skin perforation), limb rubs, russets, scab tissue, frost damage, rot, visible flesh damage and recent bruises. Camera filter effects were approximated by summing the reflectances of all the wavelengths within the filter bandwidth. Combinations of three and four filters were tested and evaluated for discriminating damaged tissues from healthy ones. If a three-filter combination appeared sufficient to detect most of the damaged tissue, a four-filter combination should be considered for the complete sorting automation of this bicolour apple variety. A fourth filter was necessary to quantify the ratio between the blush and ground colours. Regarding recent bruise defects which represented the major difficulty, an image segmentation algorithm based on local contrast variations can enhance their detection. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

A non-destructive mechanical sensor (Cantifruit) was designed to measure the firmness of tomatoes. It consists of a small plunger constrained to penetrate slightly into the fruits, by using an accurate ... [more ▼]

A non-destructive mechanical sensor (Cantifruit) was designed to measure the firmness of tomatoes. It consists of a small plunger constrained to penetrate slightly into the fruits, by using an accurate lever mechanism. A highly significant correlation exists between firmness measurements performed with this device and the Stable Micro Systems (SMS), fitted with the same plunger dimaeter. Using the Cantifruit, data related to firmness variability and changes are easily obtained. The firmness of tomatoes varies about 12 % around its circumference. In a single lot of tomatoes picked at the same time, the variability may exceed 25 %. If the tomatoes are stored at 4-5 °C and 92-99 % relative humidity (RH), their firmness decreases by about 20 % over ten days. [less ▲]